List obsolete git branches

When using git in a project it is easy to create lots of branches. This is one of the strengths of git, but it can also mean that the local branch list gets quite long. I created an alias for the command below to get an overview of which branches I can delete, and also to check if there's anything I've worked on that I might have forgotten.

git for-each-ref --sort=-committerdate refs/heads/ --format='%(HEAD) %(color:yellow)%(refname:short)%(color:reset) - %(contents:subject) - %(authorname) (%(color:green)%(committerdate:relative)%(color:reset))'